As described in Internet Engineering Task Force (“IETF”) Internet Draft entitled “Virtual Private Wire Service support in Ethernet VPN,” (hereinafter “IETF EVPN-VPWS Draft”), an Ethernet Private Line (“EPL”) and/or Ethernet Virtual Private Line (“EVPL”) may be overlayed on an Internet Protocol/Multi Path Label Switching (“IP/MPLS”) core network. IETF EVPN-VPWS Draft further describes how forwarding is constructed and how various service instance IDs may be connected. In particular, in a VPWS service, the traffic from an originating Ethernet Segment (“ES”) may be forwarded to a single destination ES; therefore, no MAC lookup is needed and an MPLS label associated with a per-EVPN instance (“EVI”) Ethernet auto-discovery (“A-D”) route may be used in forwarding user traffic to the destination attachment circuit (“AC”).
The IETF EVPN-VPWS Draft fails to address how to implement preferred path local switching in the context of EVPN-VPWS. By default, EVPN-VPWS attempts to establish a circuit across the EVPN-VPWS domain in every case; local knowledge of other EVPN-VPWS configured circuits is not considered during circuit establishment.